Many industrial facilities, such as large metallurgical smelters, steel industry pickling lines, semiconductor fabrication facilities, pulp and paper plants, inorganic chemical facilities, and power generation plants, generate extremely corrosive exhaust fumes, smoke, and particles during their operational processes. Various ductwork systems can be employed to remove or filter these hazardous wastes from the facilities. The ductwork systems are typically fabricated from combustible plastics such as polypropylene, chlorinated polyvinyl chloride, and fiberglass reinforced plastic. The ducts can be up to twelve feet in diameter, and can be hundreds of feet long, with various interconnecting vessels. Loss of a ductwork system due to fire can result in total shutdown of a key process or the entire plant for an extended period of time, and can lead to sizeable losses.
The environment inside the ductwork systems is typically extremely corrosive. High concentrations of inorganic acids, such as sulfuric, nitric, and hydrochloric acids, are often present in the ducts. In addition, the temperature inside the ducts may be very high, sometimes 100° C. or higher, and abrasive particles, such as metal, dust, and ash, may pass through the ducts at a high velocity, for example 40 miles/hour, or more. Thus, the environment inside the ducts can rapidly corrode or otherwise damage metallic structures, such as fire protection components (e.g., sprinkler nozzles).
Sprinkler nozzles have been developed that can withstand the highly corrosive environments mentioned above, for example, the sprinkler nozzles described in applicant's co-owned U.S. Patent Application Publication No. 2008/0308285 A1, the entire content of which is expressly incorporated herein by reference.
In order to prevent corrosive gasses from entering the sprinkler nozzle and/or associated piping, it is advantageous to fit a plug inside the nozzle orifice. However, high flow rates and/or turbulence inside the ductwork systems can cause the plugs to become dislodged from the nozzle orifice, and lost. In addition, conventional plugs and their retention means may tend to deteriorate under highly corrosive and extremely corrosive conditions. Furthermore, the sprinkler nozzle threads utilizing conventional sealing methods are vulnerable to corrosion and may tend to deteriorate under highly corrosive and extremely corrosive conditions. Accordingly, there remains a need in the art for nozzle plugs, sealing rings, and leashes that overcome these and other drawbacks of the prior art.